If you're a woman between 20 and 50, you have lived through – and probably paid to participate in – at least one of the following: "strippercise"; trampolining; jump rope; belly-dancing; trapeze artistry; water yoga, aerial yoga, naked yoga; pole-dancing. Some of us even went to that class at Equinox where a version of '80s aerobics is combined with theories in motivational psychology: the one where, while bouncing around, an instructor exhorted us to shout mantras such as (I blush even to type this) "I am worth it!" and "I am proud!".

The goal, as ever, was either to lose weight or arrest the sense of incremental collapse that comes with age and too many croissants, plus something on which Don DeLillo put his finger in Underworld – a kind of generational over-confidence based on the delusion that we ultimately control our own destinies: "they were training to live forever".

Apart from death, certain other facts remain immutable – primarily, that leaving the house never gets any easier but parting us from our money does. The fitness industry generated an estimated $25bn in revenue in the US in 2013, while globally, the health club industry raked in $75bn. Like the diet industry, the fitness industry's revenues rely on teasing new interest from us every few years with miracle cures and novelty classes, the latest of which is a contact version of musical chairs.

I'm kidding; it's really an updated version of hopscotch, through which practitioners learn balance and agility by hopping from one square to the next while someone in a headset shouts at them through a mirror.

No, actually, it's hula-hooping. Adult women – and these whimsical fads all tend to be aimed at women, while the men are off heaving medicine balls around Barry's Bootcamp – are apparently now gathering in studios to learn, or relearn, how to keep a hula-hoop in motion around their mid-sections.

The key facts are: it is great for your abs, burning around 200 calories in 30 minutes. Michele Obama did it once. So did Zooey Deschanel. And it played a big role in Kelly Osbourne's "weight loss journey". Need I say more?

The extraordinary thing about these trends is how quickly those people purporting to be experts in them seem to surface, like those guys who materialize at the mouth of the subway selling umbrellas the second the rain starts to fall. Where do they come from, these people with fully realized theories about stuff that didn't exist a year earlier?

Professional hula-hooping is a branch of rhythmic gymnastics, or dance, but that's not where the majority of "certified hula hoop instructors" come from. They are graduates of newly minted training courses that teach them how to "break hoop moves down into a science", and, of course, how to motivate people to "achieve their fitness goals". There is even a distance learning option, with a set of video tutorials.

There is nothing wrong with any of this per se, although, as with so many activities with an emphasis on "play", hula-hooping has the power to depress the spirit as only organized fun really can.

And the tacked on mind/body element – classes offer "to quiet the mind, and rejuvenate the spirit" – makes you want to sign up instantly for CrossFit, where they'll beat you to a pulp and leave your spirit alone.

But the thing that really irritates about this kind of fitness trend is the assumption that, because women – irrespective of age, class, IQ or experience – are on the whole desperate to be thinner, they will check their faculties at the door on the slightest promise of attainment.

Spin classes are the most successful recent manipulator of this desire, offering not just an endorphin rush, but all the woo-woo bullshit that a shouty drop-out from showbiz can deliver in 45 minutes. The language of these classes often assumes damage on the part of attendees. You can do it. You can work harder. You can reach higher and find a better version of you. Oh, fuck off.

That one of Soul Cycle's founders, Elizabeth Cutler, was a real estate broker in a previous life seems somehow perfect. (I've enjoyed the odd Soul Cycle class, but it's hard not to see that particular franchise, with its $30-plus classes, $50-plus t-shirts and grimly upbeat instructors as the exercise version of everything that is wrong with New York. You'll get more spiritual enlightenment from a bear in the woods.)

It makes the fitness trends of yore look positively charming: Jane Fonda's work out – due for a resurgence, surely – those vibrating belt machines, thigh-master devices and La-Z-Boy chairs that did the work for you. At least they didn't come with expectations of anything other than hard work and exercise: no one was expected to have an epiphany.

Being fit makes you feel better, but the corporatization of the "journey" doesn't. We get what we deserve, I suppose, since we apparently can't motivate ourselves to go out for a run without paying someone to tell us what it means.

It would be nice, however, if, just once, when we wanted to hula-hoop, we did something amazing like bought a hula-hoop, found a park, and used it. End of story.